Radiolaria are microscopic marine organisms that have drifted through Earth's oceans for more than 500 million years. Though invisible to the naked eye, they create some of the most intricate and mathematically beautiful structures found in nature. Each organism forms a delicate mineral skeleton — often spherical, radial, or lattice-like — made primarily of silica, producing an endless variety of geometric patterns and symmetrical forms. More information and pictures www.formandreform.com/radiolarian/